Simulators used for medical education and training purposes do not allow for (among other things) the simulation of the unique pressure-frequency relationship that has been observed in the pericardial fluid, and which is taken advantage by the Applicant for the safe intrathoracic navigation of a probe onto the epircardial surface to help enable electrophysiological procedures, as described in the Applicant's related applications: 1. PCT International Application No. Serial No. PCT/US2008/056643, filed Mar. 12, 2008, entitled, “Access Needle Pressure Sensor Device and Method of Use” and corresponding U.S. patent application Ser. No. 12/530,830 filed Sep. 11, 2009; 2. PCT International Application No. Serial No. PCT/US2008/056816, filed Mar. 13, 2008, entitled, “Epicardial Ablation Catheter and Method of Use” and corresponding U.S. patent application Ser. No. 12/530,938 filed Sep. 11, 2009; 3. PCT International Application No. Serial No. PCT/US2008/057626, filed Mar. 20, 2008, entitled, “Electrode Catheter for Ablation Purposes and Related Method Thereof” and corresponding U.S. patent application Ser. No. 12/532,233 filed Sep. 21, 2009; and 4. PCT International Application No. Serial No. PCT/US2008/082835, filed Nov. 7, 2008, entitled, “Steerable Epicardial Pacing Catheter System Placed Via the Subxiphoid Process,” and corresponding U.S. patent application Ser. No. 12/741,710 filed May 6, 2010, all of which are incorporated by reference in their entirety.
Ventricular tachycardia is an often fatal heart arrhythmia that is responsible for roughly 500,000 deaths per year in the US alone. Radio-frequency thermal ablation can be used to treat this condition, as is also the case for atrial fibrillation which is a less lethal but even more wide-spread condition. At present, such ablations are typically carried out on the endocardial surface (inside the heart) via catheterization through the femoral artery. However, there are significant risks associated with such procedures, including stroke and thermal damage to the esophagus and phrenic nerve.
In a different approach, access to the epicardial surface is gained by needle-based sub-xyphoid puncture, with gentle movement of the tip through the diaphragm and into the pericardial space. Successful positioning at the epicardial surface is then confirmed via flush of contrast agent within the pericardium, thus revealing the cardiac silhouette on fluoroscopy. Thereafter, a guidewire is placed through the needle and into the pericardium. The needle is then removed, and a sheath is placed over the guidewire to allow for passage of the ablation catheter to treat the electrically misfiring zones of myocardial tissue.
While a safe and workable technique in skilled hands, there is a learning curve involved and the most significant risk associated with it is inadvertent penetration of the right ventricle by the access needle, a situation that calls for immediate surgical intervention to seal the perforation. In order to minimize this risk, in related patent applications (See 1. PCT International Application No. Serial No. PCT/US2008/056643, filed Mar. 12, 2008, entitled, “Access Needle Pressure Sensor Device and Method of Use” and corresponding U.S. patent application Ser. No. 12/530,830 filed Sep. 11, 2009; 2. PCT International Application No. Serial No. PCT/US2008/056816, filed Mar. 13, 2008, entitled, “Epicardial Ablation Catheter and Method of Use” and corresponding U.S. patent application Ser. No. 12/530,938 filed Sep. 11, 2009; 3. PCT International Application No. Serial No. PCT/US2008/057626, filed Mar. 20, 2008, entitled, “Electrode Catheter for Ablation Purposes and Related Method Thereof” and corresponding U.S. patent application Ser. No. 12/532,233 filed Sep. 21, 2009; and 4. PCT International Application No. Serial No. PCT/US2008/082835, filed Nov. 7, 2008, entitled, “Steerable Epicardial Pacing Catheter System Placed Via the Subxiphoid Process,” and corresponding U.S. patent application Ser. No. 12/741,710 filed May 6, 2010.), the Applicant has introduced the concept of pressure-frequency monitoring at the needle's tip. By incorporating a pressure sensor within the distal tip of the needle, the slow steady ac signal associated with the breathing rate of the intubated patients (typically 11 to 12 breaths per minute) is detected while the needle is within the thorax. Then, when the needle's tip arrives at and enters the pericardium, a higher frequency component (at the heart rate, 60 to 90 beats per minute) is superimposed on the lower frequency one. A real-time spectral analysis or beat-to-beat analysis of the signal during the access procedure can thus provide the clinician with a “stop/go” indicator that will keep them from advancing the needle too far and perforating the heart.
Accordingly, an aspect of an embodiment of the present invention provides, but not limited thereto, the ability to train physicians to replace the existing qualitative approach of needle navigation with a decidedly quantitative one, thus making it possible for electrophysiologists to do this procedure more routinely.